Project 4: Development of a Conceptual Stratigraphic Model for the Paducah Gaseous Diffusion Plant and Vicinity
PRINCIPAL INVESTIGATORS
Dr. Alan Fryar, Associate Professor, Department of Geological Sciences, University of Kentucky
Dr. Stephen Greb, Geologist, Energy and Minerals Section, Kentucky Geological Survey, University of Kentucky
BACKGROUND
Accurate modeling of regional groundwater flow and contaminant transport depends upon accurately characterizing the spatial distribution of hydraulic conductivity (K, the permeability of porous media to water). Numerical models of the PGDP area have assumed that K values are relatively uniform within individual flow units, such as the Regional Gravel Aquifer. However, the heterogeneity of sediments within the PGDP area makes it likely that the distribution of K values is more complicated than currently modeled. Site investigations have provided subsurface lithologic logs for hundreds of monitoring wells and borings. Despite preliminary efforts by various contractors, these logs have not been used to develop detailed correlations of sedimentary units across the study area. In addition, sedimentary exposures along streams in the vicinity of PGDP have not been systematically described beyond the relatively simple geologic quadrangle (GQ) maps published by the US Geological Survey in 1966–67. We propose to integrate lithologic logs, outcrop mapping, and shallow, high resolution seismic surveys already conducted by UK Geological Sciences personnel to provide a stratigraphic framework model of the PGDP area. This detailed, conceptual model would underpin a more realistic groundwater flow model and could be also useful for assessing local amplification of earthquake ground motion by near-surface sediments.
GOALS
1. To develop a detailed, conceptual model of the stratigraphic framework in the PGDP area.
1. Compile lithologic logs from site investigations in a geographic information system (GIS) using ArcView. These logs will be taken from borings and monitoring wells drilled as part of remedial investigations at PGDP; from foundation borings for the TVA Shawnee Plant; and from other borings and wells noted on the Joppa and Heath GQ maps. To the extent possible, this compilation will augment, rather than duplicate, the compilation undertaken by the US Army Corps of Engineers for Bechtel Jacobs.
2. Map exposures along Little Bayou and Bayou creeks and their tributaries. Using the Joppa and Heath GQ maps as a guide, lithologic contacts (e.g., mud, sand, gravel, and cobbles) will be mapped along stream banks and beds. Outcrop exposures will be located for entry into the GIS using a global positioning system receiver. To differentiate between modern alluvium and older units such as the Continental Deposits, wood samples will be collected from selected outcrops for radiocarbon dating. As appropriate, we will seek advice from other geologists with regional expertise (e.g., Dr. John Nelson [Illinois State Geological Survey], who has mapped stream exposures in southern Illinois).
3. Correlate sedimentary facies in areal and cross-sectional views using ArcView, Surfer, and RockWorks 2002. Lithologic logs, outcrop exposures, and high-resolution, shallow seismic surveys collected by Christina Langston and Dr. Ron Street (formerly of the UK Department of Geological Sciences) will be used to delineate stratigraphic contacts and map hydrostratigraphic unit (HSU) thicknesses. To the extent practicable, HSU designations will follow those used previously by PGDP contractors.
TIME FRAME
Two years.
DELIVERABLES
1. End of year 1: lithologic logs will have been compiled and entered into ArcView along with mapped exposures.
2. End of year 2: final project report, including stratigraphic correlations and sedimentary thickness (isopach) maps in digital format(s). The final report will also identify instances in which additional data would be useful, such as regions where no stratigraphic information exists.
TEAM MEMBERS
Dr. Alan Fryar, Associate Professor, Department of Geological Sciences, University of Kentucky
Dr. Stephen Greb, Geologist, Energy and Minerals Section, Kentucky Geological Survey, University of Kentucky
Dr. Edward Woolery, Assistant Professor, Department of Geological Sciences, University of Kentucky
One half-time, MS-level research assistant (to be named)
Steven Hampson, Assistant Director, Kentucky Research Consortium for Energy and Environment, University of Kentucky
REPORTS
Geologic Mapping of Near-Surface Sediments in the Northern Mississippi Embayment
KRCEE is a collaborative effort of Kentucky universities and is administered by the University of Kentucky.
